Point contact-restricted cAMP signaling controls ephrin-A5-induced axon repulsion

Abstract

Signal transduction downstream of axon guidance molecules is essential to steer developing axons. Second messengers including cAMP are key molecules shared by a multitude of signaling pathways and are required for a wide range of cellular processes including axon pathfinding. Yet, how these signaling molecules achieve specificity for each of their downstream pathways remains elusive. Subcellular compartmentation emerged as a flexible strategy to reach such a specificity. Here, we show that point contact-restricted cAMP signals control ephrin-A5-evoked axon repulsion in vitro by modulating Focal Adhesion Kinase phosphorylation and the assembly and disassembly rate of point contacts. Consistently, preventing point contact-specific cAMP signals, in developing retinal ganglion cells in vivo alters the refinement of their terminal axonal arbor in the brain. Altogether, our study identifies point contacts as a compartment containing a local cAMP signal required for ephrin-A5-dependent axon guidance and highlights the crucial role of such subcellularly restricted second messenger signals in the wiring of neuronal circuits.